How does aldosterone affect potassium secretion in the principal cells of the collecting ducts?

Aldosterone increases potassium secretion by the principal cells of the distal convoluted tubule and collecting ducts. While stimulating those cells to reabsorb sodium, aldosterone simultaneously enhances potassium secretion into the filtrate. This increased secretion helps the body excrete excess potassium and is regulated by the potassium concentration in the extracellular fluid.

In the principal cells of the DCT and collecting ducts, aldosterone acts to increase sodium reabsorption and simultaneously enhance potassium secretion. The extracellular potassium concentration is the single most important factor influencing potassium secretion: when it rises, adrenal cortical cells are stimulated to release aldosterone, which in turn increases potassium secretion by the principal cells. This creates a negative feedback loop in which potassium controls its own ECF concentration. Conversely, when ECF potassium is abnormally low, principal cells reduce potassium secretion to conserve it, and type A intercalated cells can reabsorb some potassium from the filtrate. Aldosterone is also released in response to the renin-angiotensin-aldosterone mechanism, but opposing effects on sodium and potassium are normally balanced by compensatory kidney mechanisms.